Go If/Else and For Loops

If / Else

Go's if statement doesn't require parentheses around the condition, but curly braces are mandatory:

age := 18

if age >= 18 {
    fmt.Println("Adult")
} else if age >= 13 {
    fmt.Println("Teenager")
} else {
    fmt.Println("Child")
}

If with initialization statement

// v is scoped to the if/else block
if v := getValue(); v > 100 {
    fmt.Println("Large:", v)
} else {
    fmt.Println("Small:", v)
}

Switch statement

day := "Monday"
switch day {
case "Saturday", "Sunday":
    fmt.Println("Weekend!")
case "Monday":
    fmt.Println("Start of the week")
default:
    fmt.Println("Weekday")
}

For loop — the only loop in Go

// Classic C-style for
for i := 0; i < 5; i++ {
    fmt.Println(i)
}

// While-style (condition only)
n := 1
for n < 100 {
    n *= 2
}

// Infinite loop
for {
    // break to exit
    break
}

Range — iterate over collections

nums := []int{2, 3, 4}
for i, v := range nums {
    fmt.Printf("index %d: value %d
", i, v)
}

// Ignore index with _
for _, v := range nums {
    fmt.Println(v)
}